Method of electrically welding metal joists and the like



G. A. HUGHES Dec. 12, 1933.

METHOD OF ELECTRICALLY WELDING METAL JOISTS AND THE LIKE Filed Nov. 24, 1950 2 Sheets-Sheet l a a INVENTORJ GrWe/Aflug/ms, BY A v.

MQQWR UNQN Dec. 12, 1933.

G. A. HUGHES I METHOD OF ELECTRICALLY WELDING METAL JOISTS AND THE LIKE Filed Nov. 24, 1930 2 Sheets-Sheet 2 IN VEN TOR.

ATTORNEY.

Graveiflfiuykas BY Patented Dec. 12, 1933 PATENT OFFICE METHOD OF ELECTRICALLY WELDmG METAL JOISTS AND THE LIKE Grover A. Hughes, Youngstown, Ohio, assignor to Truscon Steel Company, Youngstown, Ohio, a corporation of Michigan Application November 24, 1930 Serial No. 497,906

8 Claims.

The present invention relates to a method of securing together metallic members and more particularly the bars or chords of open or skeleton beams, such as joists. It has been the practice heretofore to interpose between the ends of the chord members of such joists a steel plate and to arc-weld the same on both sides to the top and bottom chord members.

The object of the present invention is to provide a method by which the parts can be successfully secured together by resistance welding, thereby producing as strong a connection, and yet one that can be much more quickly and cheaply efiected. The means for carrying out the present novel method and the different stages of the article are shown in the accompanying drawings, wherein:

Figure 1 is a side elevation of an open or skeleton joist in which the parts have been secured by the method constituting the subject-matter of the present invention.

Figure 2 is a detail side elevation of cooperating ends'of the chord members in position to be welded together.

Figure 3 is a view similar to Figure 2, but illustrating the relation of the parts during and 'at the completion of the welding operation.

Figure 4 is a cross sectional view on the line 44 of Figure 3.

Figure 5 is a detail perspective view of the interposed elements or slugs.

Figure 6 is a view similar to Figure 3, but illustrating a different form of interposed element or slug.

Figure '7 is a cross sectional view on the line '77 of Figure 6.

Figure 8 is a detail perspective view of the connecting element or slug shown in Figures 6 and 7.

Referring initially to Figure 1, for the purposes 40 of illustration, a skeleton beam is disclosed, consisting of an upper chord member" 9, a lower chord member 10, and a web formed by a zigzag or serpentine rod 11 having its elbows 12 welded alternately to the two chords 9 and 10. The end portions of the lower chord are bent upwardly,

as shown at 13, and the terminals 14 are bent so as to lie parallel to the terminals of the upper chord 9, but in slightly spaced relation thereto. It is these terminals that are secured together by the novel method, as shown particularly in Figure 4.

The chords are formed of T-bars, comprising a flat strip or body 15 with an inset longitudinal central flange 16, the two flanges 16 being disposed in opposition. These bars have a definite carbon and manganese content, as herein exemplified. Placed between the flanges 16, are the tie elements or slugs designated 17 and 18, two being shown, though one or more being utilizable. Each of these slugs is preferably of steel, and 0 while, as shown, is much less in size than the bar and the flanges 16, has a higher carbon and manganese content.

The tie elements or slugs being interposed as indicated in Figure 2, welding electrodes 19 are brought against the outer sides of the ends of the bars and force said bars against the slugs 17 and 18. At the same time an electric current is passed across the bars and through the slugs, this current having sufficient strength to fuse the metal of the slugs and of course also fuse the metal of the bars where these slugs contact therewith. The consequence is that the metals of the bars and interposed elements amalgamate so that a welding eirect takes place. As a matter of fact, the slugs will embed themselves in the flanges of the bars-due to the fusing of the metal and the pressure of the electrodes. The result is that an exceedingly strong connection is secured between the bars and one that can be expeditiously and oheaplyobtained.

This appears to be due to the fact that the heat of the electric circuit is produced in proportion to the resistance. The area of contact of the electrodes 19 with the bars 9 and 10 is relatively great so that the resistance at this point is low. The resistance between the flanges l6 and the slugs or tie, elements 17 and 18 will however, be relatively high as the contact area is small. The heat generated at the points of contact is determined by the drop in voltage multiplied by the current flowing. It is therefore obvious that the slugs or tie elements 17 and 18 haveas much heat generated in them as is generated in the bars combined. It will be obvious that the loss of contact heat by conduction in said bars is much greater than in the slugs, owing to the greater mass of the former. It thus follows that the slugs heat much more rapidly than the bars as the current is passed from one of the electrodes to the other. However, as the slugs are' heated their crushing strength is reduced,and if these slugs were made of ordinary structural grade steel, there is a tendency that they will be upset, forcing part of the metal over areas of the two bars that are not at fusing temperature, resulting in poor fusion or perhaps no fusion and a consequently weak connection. The slugs therefore must be kept below the temperature where they will be crushed or upset by the pressure brought upon them through the medium of the electrodes and at the same time the contacting portions must be kept at a fusing temperature. The resistance of the steel to the flow of the current increases with the carbon and manganese content of said steel. The yield point ofthe steel increases with the carbon and manganese content thereof and.

the'resistance to the crushing action increases with the yield point. It will thus be seen that if the carbon and manganese content of the frame bars 9 and 10 is low, as compared to that of the slugs or tie elements 17 and 18, the crushing strength of the latter is above that of the bars. The resistance of the slugs 17 and 18 to the flow of the current across the bars is increased. Consequently the surfaces of the bars which are in contact with the slugs are brought to a fusing temperature before the heat is conducted away, and while the surfaces of the slugs are caused to fuse, the slugs are not materially upset, and as a result effective fusion is obtained;

' As examples of the results that have been obtained on tests of the structures produced in accordance with this method, the following are given.

In each of the following tests the chemical analysis of the bars used showed a carbon content of .18 and a manganese content of .40.

Where the tie elements or slugs had a carbon content of .12 and of manganese .41, the welds resisted a pulling strain of separation ranging between 12000 and 13100 lbs. An increase of the carbon content to .15 and the reduction of the manganese to .30 made an effective resistance to a separation strain ranging between 18080 and 19000 lbs. A carbon content of .18 and of manganese .36 increased the resistance to, the breaking strain by making the range from 20100 to 22040 lbs. Where the carbon and manganese contents were respectively .23 and .60, the bars withstood a strain of 24450 lbs. An increase of the carbon to .29 and the manganese to .63 increased the breakage resistance to a range varying between 27300 to 29800 lbs. and where the carbon content of the slugs was .33 and the manganese .65,.the bars withstood a separating strain ranging from 28700 to 30800 lbs.

The type of slug or tie element may be varied, and as an example the disclosure shown in Figures 6, 7 and 8 is made. In these views the upper chord member or bar is designated 9a and the lower chord or bar 10a, these bars having inwardly extending flanges 16a. The tie element in this case is U-shaped, comprising a bar having offset terminals 17a and 18a that are placed between the flanges 16a'of the bars 9a and 10a, but with the main body of this bar preferably spaced from the flanges, so that the terminals only are in contact. The electrodes are shown at 19a. It will be understood that this element I'm-18a has the higher carbon and manganese content, or in other wordshas a greater resistance to the flow of the electric current than have v the bars .Qa-and 10a. The

terminals are interposed between the flanges and the electrodes 19a are moved inwardly to press the bars against the terminals, while a welding current of suflicient strength to fuse the metal is passed across the bars and terminals through the electrodes 19a.

v From the foregoing, it is thought that the construction, operation and many'advantages of the herein described invention will be apparent to those skilled in the art without further description and it will be understood that various changes in the size, shape, proportion and minor details of construction may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention.

What I claim, is:

1. In the art of electric welding, the steps of applying to a metallic member of material size, a metallic element of smaller size and having a higher melting point than the corresponding portions of said member with which it contacts and welding together the member and element by passing an electric current through said member and element of sufficient strength to cause the metal of both to fuse together.

2. In the art of electric welding, the steps of contacting a metallic member of material size and a metallic element of materially less size, having a higher melting point and greater electrical resistance than the coresponding portions of the member with which it contacts, passing through said member and element an electric current of suflicient strength to fuse the con- ,tacting portions of both members and element,

and forcing the said member and element together to cause the element to become embedded in the member.

3. In the art of electric welding, the steps of interposing between two metal members to be connected, an element of less size, havingahigher melting point and greater electrical resistance than the corresponding portions of the metal members that it contacts and passing an electric current through the members and the interposed element of suflicient strength to cause a welding action to take place between the members and element.

4. In the art of electrically welding together metallic frame bars, the steps of interposing between said bars a metallic element having a smaller area, a higher melting point and greater electrical resistance than the portions of the bars with which it contacts, and passing through said metallic frame bars, the step of interposing between said bars a metallic element having a smaller area, a higher melting point and greater electrical resistance than the portions of the bars with which it contacts, passing through said bars and through the element an electric current of suflicient strength to fuse the metal of the bars.

and interposed element together, and causing the element to become embedded the bars.

6. That improvement in the art of connecting metallic frame bars having a carbon and manganese content, which consists in placing saidbars side by side, interposingbetween them, a metal element of less size and having a greater carbon and manganese content than the bars, forcing said bars towards each other and against the element, and passing through the bars and elementan electric current of sufficient strength to fuse together the contact portions of the bars and element.

7. In the 'art of connecting metallic frame bars having a carbon and manganese content, which consists in placing said bars side by side, interposing between them' a plurality of metallic elements of less size and having a greater carbon and manganese content than the bars, forcing said bars towards each other and against the elements and passing through the bare and elehaving a manganese content greater than that of the bars, forcing said bars towards each other and against said terminals, and passing through the bars and through the terminals an electric current of sufllcient strength to fuse together the contacting portions of the bars and said terminals.

' GROVER A. HUGHES. 

